Table 2. Number and percentage of studies reporting external validity elements ¹.

External validity dimension	Definition	Studies reporting
		Yes/Total 2	%
Reach and representativeness of individuals
Target population for generalizability	Is the intended target population acknowledged/stated (at the individual level) for which the findings intend to be generalised to?	38/39	97
Method to recruit target population	Was information provided about how the target population was recruited/ reached (e.g., radio, newspaper, TV, school meeting)?	30/39	77
Inclusion or exclusion criteria	Were individual inclusion and exclusion criteria stated?	38/39	97
Enrolment rate	Is the enrolment rate or data needed to calculate the enrolment rate among individuals reported? Proportion of people who are eligible for participation who actually enrol in the study	26/39	67
Recruitment rate	Is the recruitment rate or data needed to calculate the recruitment rate among individuals reported? Proportion of potential participants (those invited or expressing interest) who actually enrol in the study	26/39	67
Representativeness of individuals	Are there comparisons between individuals who participated versus either (1) those who declined to participate or (2) target population?	10/39	26
Participant characteristics	Are all of the following reported: •Gender •Age •Any socioeconomic indicators (education, employment status, or income) •Participation by racial or ethnic minority groups	21/39	54
Reach and representativeness of settings
Target setting	Is the target setting for intervention delivery stated (such as workplace, general practice, outpatient facilities, churches, etc.)?	35/38	92
Method to recruit setting	Is information provided about how the site(s) within a given setting were recruited/reached to participate in delivering the intervention?	4/28	14
Inclusion or exclusion criteria	Were inclusion and exclusion criteria for selection of sites within a given setting stated? In the case of single sites, were the characteristics of the site described?	6/28	21
Participation rate	Is the participation level or data need to calculate the participation level among eligible sites reported (only applies to studies with more than one site)?	1/19	5
Representativeness of setting(s)	Are there comparisons between site(s) participating in the intervention and 1) those that decline to participate or 2) the target setting?	1/28	4
Implementation and adaptation
Intervention characteristics	Were the intervention components described?	38/39	97
Intervention adaptation	Is information reported about how the study intervention is similar or different to original efficacy studies? Note: Only applicable to studies where an intervention is adapted from a previous trial	0/5	0
Time to deliver intervention described	Is the number and length of sessions or time required to deliver the intervention described?	24/37	65
Intervention delivery and exposure	Was the extent to which individuals were exposed to the intervention described? (e.g. proportion of planned intervention sessions actually attended (dose); content delivered as specified; provider adherence to intervention plan)	24/37	65
Delivery agents: characteristics and training	Is information provided on who delivered the intervention, such as the type of professional, or the amount of experience, skill or training required to deliver the intervention?	37/39	95
Methods to recruit delivery agents	Is information provided about how the delivery agents were identified/selected?	3/36	8
Delivery agents’ participation	Is the participation level amongst delivery agents reported (% of delivery agents agreeing to participate)?	4/35	11
Fidelity assessment: treatment receipt	Is information reported about whether the program was received as intended? (e.g. degree to which the participants understood the intervention and/or ability to perform the intervention skills)	4/39	10
Mechanisms for intervention effects	Was retrospective analysis conducted to identify the mediating variables through which the intervention achieved its effect?	2/39	5
Outcomes for decision making
Outcomes that can be compared to standards	Are outcomes (at least one) reported in a way that can be compared to either clinical targets or public health goals?	36/39	92
Adverse consequences	Does the article report whether they examined the occurrence of unintended consequences?	18/39	46
Effect moderators by participant characteristics	Are there any analyses of moderator effects by subgroups of participants	10/39	26
Effect moderator by delivery agent/ setting	Are there any analyses of moderator effects by delivery agents or settings	0/37	0
Dose response effect of intervention (sensitivity)	Are there sensitivity analyses to assess dose-response effects of the intervention?	1/39	3
Total costs of intervention	Are total costs of the intervention presented?	6/39	15
Cost of intervention components	If costs are presented, were the costs itemized by intervention components (e.g., personnel, equipment)?	4/6	67
Cost effectiveness	If costs are presented, was there any analysis done to assess cost- effectiveness or cost-benefit of the program or policy?	3/6	50
Maintenance / institutionalisation
Long term effects (at least 12 months) 3	Are data reported on longer term effects on health-related outcomes, at least 12 months following program implementation, or environmental or policy change?	19/39	49
Institutionalization: sustainability / plans for sustainability	Are data reported on the sustainability (or reinvention or evolution) or plans for sustainability of the intervention?	4/39	10
Attrition	Are data reported on the number of individuals dropping out and/or lost to follow up	38/39	97
Differential attrition (by condition or population sub-group)	Are data on attrition by condition or population sub-group reported?	35/39	90
Representativeness of completers/ dropouts	Did the study report statistically significant differences in those that dropped out of treatment and those that finished?	19/38	50
Acceptability of the intervention by stakeholders	Was information provided about acceptability of the intervention by stakeholders?	14/39	36

Notes:

¹Laws et al. (adapted from Green et al.)

²Total = the no. of overall studies (n=39) minus the no. of studies reporting not applicable to the relevant element

³In RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance), long-term results of intervention are defined as a minimum of six months following the last contact; long-term is defined as a minimum of 12 months by Laws et al.